Vascular bundles :(a) It is in the form of several alternate and radial xylem and phloem bundles. (b) The number is 20-30 in maize. (c) In many cases the vascular bundles are embedded in a cylinder of sclerenchymatous conjunctive tissue.(d) The vascular bundles are arranged in the form of ring around a central pith. (e) The xylem bundles are exarch, i.e., protoxylem lies towards the outside while the metaxylem faces inward. Because of the presence of numerous xylem bundles and exarch condition, xylem of monocot root is polyarch.(f) Xylem is made up of rounded or oval vessels, and are narrow. (g) They have a spiral annular or reticular thickenings(h) Xylem provides mechanical strength and helps in the conduction of water and mineral salts. (i) Phloem bundles alternate with the xylem bundles.These two are separated from each other by means of narrow strip of conjunctive tissue.(j) The cells of this tissue store food if parenchymatous. (k) They provide mechanical strength on becoming sclerified. (l)They do not take part in the formation of cambium.(m) Phloem consists of sieve tubes and companion cells.It helps in the conduction of organic food.